The first example of fluorescence of the solid individual compounds of Eu 2+ ion: EuCl 2 , EuI 2 , EuBr 2

Fluorescence (FL) from Eu 2+ ion solid individual compounds was observed for the first time using the examples EuCl 2 , EuI 2 and EuBr 2 . Fluorescence was detected at excitation by ultraviolet (UV) light from powdered samples of Eu (II) halides at room temperature (RT) in an argon atmosphere. In air, FL of all Eu 2+ compounds studied was stable, and intensity persisted for weeks. Depending on the nature of the halide anion and due to a nephelauxetic effect, the position of the maxima in the FL spectra underwent a red shift in the series: EuCl 2 (409 nm) < EuBr 2 (428 mm) < EuI 2 (432 nm). The lifetimes of the excited states of the Eu 2+ * ions for EuI 2 , EuCl 2 and EuBr 2 were 355, 76 and 54 ns, respectively.